A conventional plug-and-socket connector assembly normally includes an electrical plug connector and an electrical socket connector. The electrical plug connector includes a main body with a plurality of plug pins, and a shroud extending to surround the plug pins. The electrical socket connector has a plurality of socket holes for respectively receiving the plug pins, a plurality of terminals disposed respectively in the socket holes for electrical contact respectively with the plug pins, and an annular groove for receiving the shroud. U.S. Pat. No. 4,493,517 discloses a conventional electrical socket connector. Sometimes, the electrical plug connector may be undesirably detached from the electrical socket connector.